Many electronic devices have an amount of time during which operation occurs. Some electronic devices, such as a washing machine may have a predetermined amount of time to operate a complete cycle. Other electronic devices, such as an oven or a microwave, may permit a user to set (i.e., program) a time for operation. Some electronic devices may have both predetermined times as well as programmable times set by a user in order to operate. At times, a user may initiate operation of the electronic device and then leave the electronic device.
For example, energetic initiation devices are often employed in military, commercial, and police use. An energetic initiation device is generally configured to initiate (i.e., fire) a wide range of explosive devices, such as shock tubes, blasting caps, and electrically primed cartridges. Such energetic initiation devices may include a countdown circuit that permits a user to program a desired countdown time for the energetic initiation device to fire after the energetic initiation device has been armed. For example, a user can begin the process of a firing by starting the countdown. The user can then retreat to a safe distance during the countdown time.
FIG. 1 illustrates a conventional electronic firing system 100. The conventional electronic firing system 100 includes an initiation device 110 and an arm key 140. The initiation device 110 is configured to initiate (e.g., fire, detonate) an external device (not shown) such as a shock tube, blasting cap, or other explosive device by sending an initiation signal to the appropriate device. The arm key 140 may be configured to engage with, and be removed from, the initiation device 110 through a receptacle 145 of the initiation device 110. The arm key 140 may act as a safe and arm mechanism (e.g., mechanical out-of-line mechanism) with the initiation device 110 such that the initiation device 110 is in a safe position with the arm key 140 inserted in the initiation device 110, and in an armed position with the arm key 140 removed from the initiation device 110. Removal of the arm key 140 may cause the initiation device 110 to enter into a countdown routine to provide a time delay prior to sending the initiation signal.
The initiation device 110 includes a housing 111 configured to house the internal electronics (not shown). The external portion of the housing 111 of the initiation device 110 includes a programming interface 125 and a display 114. Programming interface 125 may include controls (e.g., set button 127, time buttons 129) for a user to set (i.e., program) the countdown time for the conventional electronic firing system 100. For example, in operation a user may hold down the set button 127 while adding minutes and seconds to select a desired countdown time by pressing the appropriate time buttons 129. Holding the set button 127 and pressing the time buttons 129 causes the countdown time displayed on the display 114 to change. If the user releases the set button 127, the countdown time is stored within the initiation device 110 of the conventional electronic firing system 100. The display 114 is configured to show the countdown time during programming. The display 114 may also be configured to show the countdown time as the countdown time changes during a countdown routine.
The initiation device 110 further includes one or more output terminals, such as a shock tube connector 130 and a blasting cap connector 135. The shock tube connector 130 may be configured to couple with a shock tube (not shown) to be fired. The blasting cap connector 135 may be configured to couple with a blasting cap (not shown) to be fired.
In operation, a user may remove the arm key 140 as indicated by arrow 151. Removal of the arm key 140 may initiate the countdown routine based on the countdown time. The countdown time may be set to provide a sufficient time for the user and other personnel to retreat to a safe distance prior to detonation of the appropriate device to be fired. The user may retain the arm key 140 and leave the conventional electronic firing system 100 behind in the firing zone during the countdown routine. The countdown routine may be stopped prior to firing by re-inserting the arm key 140 into the receptacle 145 of the initiation device 110 of the conventional electronic firing system 100. At the end of the countdown routine, the initiation device 110 may send the appropriate initiation signal to the shock tube or the blasting cap.
In some circumstances, the display 114 on the conventional electronic firing system 100 may no longer be visible to the user. For example, the user may retreat to a sufficiently large distance, or behind a barrier, such that the countdown time on the display 114 is not clear or visible. Consequently, personnel may not be aware how much time has elapsed and whether detonation has occurred or is yet to occur. The user may also be unaware if a failure has occurred, as well as if there is sufficient time to re-insert the arm key 140 to stop the countdown routine prior to generation of the initiation signal.